Electrocatalytic activity of nanoporous Pt-Ir materials toward methanol oxidation and oxygen reduction

Nanoporous PtIr bimetallic electrocatalysts with different contents of iridium (Ir%: 15, 28, 40, and 50) were prepared using a one-step facile hydrothermal method. Formaldehyde was used as the reduction agent to simultaneously reduce Ir3+ and Pt4+, resulting in the formation of bimetallic PtIr nanoporous structures. Scanning electron microscopy and energy dispersive X-ray spectroscopy were employed to characterize the surface morphology and composition of the as-synthesized samples. A number of electrochemical methods were used to study the electrochemical activity of the different nanoporous PtIr electrodes toward methanol oxidation and oxygen reduction. Our electrochemical studies show that the synthesized nanoporous PtIr electrodes possess extraordinarily high electroactive surface areas and that the presence of Ir significantly improves the electrocatalytic activity of Pt toward the electrochemical oxidation of methanol and the electrochemical reduction of oxygen. Of the synthesized nanoporous PtIr electrodes, the Pt60Ir40 electrode exhibits the highest electrocatalytic activity. The steady-state current density of the nanoporous Pt60Ir40 electrode for methanol oxidation at 0.6 V is 345 times higher than that of a polycrystalline Pt electrode and over four times higher than that of a nanoporous Pt electrode (c) 2007 The Electrochemical Society.